It is known to use booms to provide a means to hold or support an object at an extended distance from a particular location. Conventional telescopic, or extensible, boom construction is limited because of the requirements for long massive section lengths, multiple extension means and other elements which necessitate massive structures that are hard to stabilize on mobile machinery. In the past, particularly in the large type extensible apparatus such as used in materials handling or logging industry, large oil volumes and resultant necessary horsepower have been necessary to achieve satisfactory telescopic extension and retraction speeds. Moreover, the prior art extensible grapple apparatuses, such as employed in the logging industry for example, have been limited to a reach of between 4 and 15 feet and have weighed between 3500 and 12,000 pounds. Because of their limited extensibility and because they were too heavy on steep terrain, they have not been totally satisfactory to providing a highly flexible, multi-use extensible apparatus that can be employed for automatic grapple logging or for using other work tools.
Several patents have been examined that were allegedly pertinent. Of these, the following patents were deemed not to be really close in terms of technical content: Pat. Nos. 2,865,523; 3,252,542; 3,557,967; 3,703,903; 3,708,037; and 3,828,939. One patent was found to be pertinent. That patent is U.S. Pat. No. 4,053,075 pertaining to a high lift mounting means for loader buckets, for use with Caterpiller tractor or the like. This loader is pertinent in providing a vertically extensible loader bucket made possible by double acting hydraulic cylinders that are pivotally interconnected. The approach is vastly different and the structure is vastly different from this invention, however; and the invention of U.S. Pat. No. 4,053,075 could not be employed at the variety of azimuthal and altitudinal angles with the variety of work tools that this invention enables.